Comparing the Acute Effects of a Session of Isometric Strength Training with Heavy Resistance Training on Neuromuscular Function

Abstract Purpose This study compared the acute effects of a session of isometric strength training (ISO) with heavy resistance training (HRT) training on 20-m sprint, countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) performance. Methods Ten resistance-trained athletes (age: 26.7 ± 6.2 years, body mass: 71.5 ± 16.2 kg, height: 1.68 ± 0.10 m) performed baseline measures for 20-m sprint, CMJ and IMTP prior to either an ISO or HRT session. During both training sessions, participants performed back squats, Romanian deadlift and split squat. Post-test performances were measured 5 min and 24 h after each training session. Participants returned a week later to perform the other training session. Results A significant time × condition effect was found for 20-m sprint time ( P = 0.007) and IMTP peak force ( P = 0.003). Main time effect was observed for 20-m sprint ( P < 0.001), CMJ height ( P < 0.001) and IMTP peak force ( P < 0.001). HRT resulted in a greater increase in sprint time at 5 min (0.17 ± 0.12 vs. 0.06 ± 0.05 s, P = 0.013, g = 1.15) and 24 h (0.01 ± 0.09 vs. 0.00 ± 0.05 s, P = 0.004, g = 1.32) post-training as compared to ISO. Similarly, HRT resulted in a significantly larger reduction in IMTP peak force than ISO at both 5 min (− 363.3 ± 248.8 vs. − 98.9 ± 230.3 N, P = 0.024, g = 1.06) and 24 h (− 289.2 ± 256.2 vs. 37.9 ± 177.8 N, P = 0.004, g = 1.42) post-training. Total impulses generated during each exercise were greater during ISO than HRT ( P < 0.001–0.006). Rating of perceived recovery post 24 h was higher in ISO than HRT ( P = 0.002). Conclusion The above results indicated that acute HRT led to a greater reduction in sprinting strength performance and lower perceived recovery post-24 h than ISO.